The invention concerns the general field of air navigation and air safety aids.
In EP-A-O 565 399, Applicant has proposed a device comprising:
an input for receiving status indications, capable of permitting a prediction of the path of the aircraft,
a working memory capable of containing a temporary local map from which an altitude envelope of the terrain can be defined in the zone where the aircraft is manoeuvring,
first path prediction means so as to establish a vertical limit path of the aircraft (in the vertical xe2x80x9cplanexe2x80x9d), on the basis of the said status indications and selected flight parameters.
first comparison means for effecting a first comparison between this vertical limit path and the corresponding part of the altitude envelope so as to determine a collision hazard with the ground, and
alarm means to establish at least one alarm status according to the result of the first comparison.
This solution has undeniable advantages, in that it provides an anti-collision device that is entirely on board and is above all capable of taking into account future situations of the aircraft.
However, it has been shown that certain locations, in particular the approaches of certain airports, have a topology that is of the kind which always produces an alarm even within the standard approach manoeuvres. Although it is conceivable to admit such cases by way of exception, this type of exception is pernicious: indeed an alarm system should, as a matter of principle, always intervene deliberately; otherwise one runs the risk that an alarm will be ignored at the time when it should, on the contrary, be imperatively taken into account.
This problem, known for a long time, has never been completely resolved in the known anti-collision systems.
The present invention aims to offer a solution on the basis of the above mentioned device described in EP-A-0 565 399.
According to the invention, the present invention, there is provided a device for aiding air navigation and air safety, of the type comprising:
an input for receiving status indications, capable of permitting a prediction of the path of the aircraft;
a working memory capable of containing a local altimetric map from which an altitude envelope of the terrain can be defined in the vicinity of the aircraft;
first path prediction means so as to establish a vertical limit path of the aircraft, on the basis of said status indications and selected flight parameters, in the vertical surface containing the axis of its path;
first comparison means for effecting a first comparison between this vertical limit path and the corresponding part of the altitude envelope, so as to determine a hazard of a vertical collision with the ground; and
alarm means to establish at least one alarm status according to the result of the first comparison;
second prediction means for establishing, on the basis of said status indications and selected flight parameters, a lateral limit path for the aircraft on one side of the vertical of the flight path; and
second comparison means for effecting a second comparison between this lateral limit path and the corresponding part of the altitude envelope;
wherein the alarm means (5) are arranged so as to modify at least one of the alarm statuses relating to the first comparison, if the second comparison means do not indicate any collision hazard with the ground.
Although such a device, operating only on one side of the vertical of the flight path, already provides progress, it is considered to be preferable to operate on both sides of the vertical. For this purpose, the device is completed by:
third prediction means so as to establish on the basis of said status indications and selected flight parameters another lateral limit path for the aircraft on the other side of the vertical, and
third comparison means so as to effect a third comparison between this other lateral limit path and the corresponding part of the altitude envelope,
and wherein the alarm means are arranged so as to inhibit the alarm status relating to the first comparison which indicates the maximum hazard, at least in the case where both the second and the third comparison means do not at the same time indicate any lateral collision hazard with the ground.